The present invention relates to an apparatus for absorbing a gas in an absorbing liquid. In particular, the invention relates to such an apparatus for use in an absorption process involving large heat transfers.
An example of such an apparatus is the absorber in an absorption cycle heat pump. An absorption cycle heat pump is defined as a device which transfers heat generated by the heat dissipating components of the device to a space for heating purposes or, alternately transfers heat from the space to the heat absorbing components of the device. In an absorption cycle, heat pump refrigerant is absorbed into a liquid absorbent which is cooled externally in order to increase its absorption capacity. The concentrated solution of refrigerant in absorbent is pumped to a heated generator where refrigerant vapor is driven off at an increased pressure, and the separated absorbent is returned to the absorber. The refrigerant vapor passes to a condensor where it is condensed by heat exchange with a first fluid and then flows via an expansion valve through an evaporator, where the refrigerant liquid is evaporated by heat exchange with a second fluid. The heat made available to the first fluid may be used to heat an environment. Alternately, the cooling of the second fluid by heat dissipation in the evaporator may be used for cooling a space. Heat pumps of the absorption cycle type are normally operated with water as the absorbent and ammonia as the refrigerant.
An essential part of the absorption cycle heat pumps is the absorber itself. The absorber refrigerant is caused to dissolve in a liquid absorbent solution to form a solution rich in refrigerant and heat evolved during the absorption is removed by the cooling medium passing through the absorber. The heat exchange between absorbent and cooling medium should be as high as possible for the following main reasons: 1, the capacity of a heat pump system depends upon the quantity of refrigerant which is passed through the system, the capacity may be increased by increasing the quantity of refrigerant; and 2, the efficiency of the absorber is determined by the ratio between quantity of refrigerant being circulated and the quantity of absorbent required, increase of this ratio forms an improvement of the absorber efficiency. Furthermore, if heat pumps are intended for use in locations where free space is restricted, it is a major requirement that the heat pump units, and therefore the absorber be of a compact construction.
The known absorbers in absorption cycle heat pumps fail to combine the above features of high efficiency, high capacity and compactness. Compactness of the absorbers is normally accompanied with a relatively low heat pump efficiency, while high efficiency asks for high and complicated absorber constructions.